He explains not only why Node.js is important, but what you can get done with it:

Node already has a really vibrant collection of modules which provide a range of functionality. Demystifying what's available is pretty important to actually getting stuff done with Node. Since Node itself is very low level, lots of things people expect in web servers aren't automatically there (for example, request routing). In order to help ease people into using Node this session will look at a range of the best modules for Node.js